/*
 * Copyright (c) 1988 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * Routines to decode user commands.
 *
 * This is all table driven.
 * A command table is a sequence of command descriptors.
 * Each command descriptor is a sequence of bytes with the following format:
 *      <c1><c2>...<cN><0><action>
 * The characters c1,c2,...,cN are the command string; that is,
 * the characters which the user must type.
 * It is terminated by a null <0> byte.
 * The byte after the null byte is the action code associated
 * with the command string.
 *
 * The default commands are described by cmdtable.
 */

#include <sys/param.h>
#include <sys/file.h>
#include <stdio.h>
#include <less.h>

/*
 * Command table is ordered roughly according to expected
 * frequency of use, so the common commands are near the beginning.
 */
#define CONTROL(c)              ((c)&037)

static char cmdtable[] = {
        '\r',0,                         A_F_LINE,
        '\n',0,                         A_F_LINE,
        's',0,                          A_F_LINE,
        'j',0,                          A_F_LINE,
        'k',0,                          A_B_LINE,
        'd',0,                          A_F_SCROLL,
        CONTROL('D'),0,                 A_F_SCROLL,
        'f',0,                          A_F_SCROLL,
        'u',0,                          A_B_SCROLL,
        CONTROL('U'),0,                 A_B_SCROLL,
        ' ',0,                          A_F_SCREEN,
        'z',0,                          A_F_SCREEN,
        CONTROL('F'),0,                 A_F_SCREEN,
        'b',0,                          A_B_SCREEN,
        CONTROL('B'),0,                 A_B_SCREEN,
        'R',0,                          A_FREPAINT,
        'r',0,                          A_REPAINT,
        CONTROL('L'),0,                 A_REPAINT,
        'g',0,                          A_GOLINE,
        'p',0,                          A_PERCENT,
        '%',0,                          A_PERCENT,
        'G',0,                          A_GOEND,
        '0',0,                          A_DIGIT,
        '1',0,                          A_DIGIT,
        '2',0,                          A_DIGIT,
        '3',0,                          A_DIGIT,
        '4',0,                          A_DIGIT,
        '5',0,                          A_DIGIT,
        '6',0,                          A_DIGIT,
        '7',0,                          A_DIGIT,
        '8',0,                          A_DIGIT,
        '9',0,                          A_DIGIT,

        '=',0,                          A_STAT,
        CONTROL('G'),0,                 A_STAT,
        ':','f',0,                      A_STAT,
        '/',0,                          A_F_SEARCH,
        '?',0,                          A_B_SEARCH,
        '!',0,                          A_SHELL,
        ':','!',0,                      A_SHELL,
        'n',0,                          A_AGAIN_SEARCH,
        'm',0,                          A_SETMARK,
        '\'',0,                         A_GOMARK,
        'E',0,                          A_EXAMINE,
        'N',0,                          A_NEXT_FILE,
        ':','n',0,                      A_NEXT_FILE,
        'P',0,                          A_PREV_FILE,
        ':','p',0,                      A_PREV_FILE,
        'v',0,                          A_VISUAL,

        'h',0,                          A_HELP,
        'q',0,                          A_QUIT,
        'Q',0,                          A_QUIT,
        ':','q',0,                      A_QUIT,
        ':','t',0,                      A_TAGFILE,
        ':', 'a', 0,                    A_FILE_LIST,
        'Z','Z',0,                      A_QUIT,
};

char *cmdendtable = cmdtable + sizeof(cmdtable);

#define MAX_CMDLEN      16

static char kbuf[MAX_CMDLEN+1];
static char *kp = kbuf;

/*
 * Indicate that we're not in a prefix command
 * by resetting the command buffer pointer.
 */
noprefix()
{
        kp = kbuf;
}

/*
 * Decode a command character and return the associated action.
 */
cmd_decode(c)
        int c;
{
        register int action = A_INVALID;

        /*
         * Append the new command character to the command string in kbuf.
         */
        *kp++ = c;
        *kp = '\0';

        action = cmd_search(cmdtable, cmdendtable);

        /* This is not a prefix character. */
        if (action != A_PREFIX)
                noprefix();
        return(action);
}

/*
 * Search a command table for the current command string (in kbuf).
 */
cmd_search(table, endtable)
        char *table;
        char *endtable;
{
        register char *p, *q;

        for (p = table, q = kbuf;  p < endtable;  p++, q++) {
                if (*p == *q) {
                        /*
                         * Current characters match.
                         * If we're at the end of the string, we've found it.
                         * Return the action code, which is the character
                         * after the null at the end of the string
                         * in the command table.
                         */
                        if (*p == '\0')
                                return(p[1]);
                }
                else if (*q == '\0') {
                        /*
                         * Hit the end of the user's command,
                         * but not the end of the string in the command table.
                         * The user's command is incomplete.
                         */
                        return(A_PREFIX);
                } else {
                        /*
                         * Not a match.
                         * Skip ahead to the next command in the
                         * command table, and reset the pointer
                         * to the user's command.
                         */
                        while (*p++ != '\0');
                        q = kbuf-1;
                }
        }
        /*
         * No match found in the entire command table.
         */
        return(A_INVALID);
}
